A mad killer is loose in Venice's catacombs. He attacks the beautiful women, releasing them into the underworld, kill them and then stop them and add them to his "collection".

In 1940s Venice, after twenty years' marriage, retired art critic Nino Rolfe and his younger wife Teresa feel their passion waning. To help her shed her inhibitions and rekindle their relationship, the professor records his sexual fantasies in a diary.